Cooperative relay, as an emerging technology in the field of wireless telecommunication, has the basic idea of obtaining diversity effect via independent channels. In the cooperative relay network, the source node broadcasts the signals that it needs to transmit, and part of the relay devices deployed in the network can receive these signals, and consequently process and forward the signals. In multi-relay network, the signals forwarded by said relay devices will reach relay devices on the next hop, these relay devices will process and forward the signals again, at last, said signals reach the destination (the signal destination).
As a brand new field, the cooperative relay has limited solutions. As the cooperative relay needs to combine the signals from different relay stations, many solutions for cooperative relay require accurate synchronization and power match, which set high requirements for the real implementation of the system. Other solutions require specific channel conditions, such as the orthogonality between the channels, which increase the difficulty for design and measurement. In addition, the improvement of the performance obtained by cooperative relay is also subject to the channel condition.